Optus has launched its voice over Wi-Fi service. But so far it’s strictly for Samsung Galaxy S7 and Galaxy S7 Edge users.The system will allow Optus customers with this gear to make and receive calls, as well as SMS and MMS messages, even when they’re out of reach of a reliable mobile service – as long as an accessible Wi-Fi service, such as home or public Wi-Fi, is available, Optus says.

The Wi-Fi calling (VoWI-FI) service differs from Optus’s existing Wi-Fi Talk app-based system which customers can download to their devices to make and receive calls and SMS over Wi-Fi.

“Wi-Fi Calling allows customers to stay connected if mobile coverage is limited when they are out-and-about, at home or in the office, but have access to a Wi-Fi connection,” Wong said.

“When Wi-Fi Calling is switched on, the device automatically detects and seamlessly switches to an available Wi-Fi connection to use voice and messaging services.”

The Galaxy S7 and S7 Edge are said to be the first two compatible handsets that allow seamless switching between mobile and Wi-Fi networks. Plans are under way to include more devices as they become available, Optus says.